But actually, no, our brains have always been driven by fear to some extent, according to Dean Burnett, a neuroscientist and the author of Idiot Brain: What Your Head Is Really Up To. The book, which was released in the United States last week, is an Osmosis Jones–style tour through the human brain: Here, on the left, the reason why your brain triggers motion sickness on a boat. Here, the reason why you can remember enough information about a person to write their Wikipedia entry but can't seem to remember their name. And here, the reason why singing karaoke in a crowded bar puts some people on the verge of a panic attack.

I skyped Burnett at his home in Cardiff, Wales, to talk more about how our brains evolved to be scared of everything—and why, in our modern times, it's creating an anxiety epidemic.

This interview has been edited for length and clarity.

VICE: Why are our brains so predisposed to be fearful?Dean Burnett: You have to think about the brain as evolving over millions of years. A tendency to be afraid of anything unusual seems like paranoia by our modern standards but is very good in an evolutionary sense. A branch snapping in the woods or a shadow could be, for a more simple creature, a genuine predator or threat. So a consciousness or unconscious system that constantly says, "What's that? Is it dangerous? What's that? Is it dangerous?" is a really good survival strategy.

Over time, the brain evolved to maintain that level of apprehension and watchfulness. We have a threat-detection system that takes in sensory information and tags anything unusual or unknown or potentially dangerous, based on memories and biological instinct, as scary. That's what's kept us alive for millions of years. It's just that now we've become sophisticated to the point where we've tamed our environment. It's overkill.

Right. Like, there's no good reason for me to be scared of insects, but I am. You also mention in your book how some people are too scared to get up and sing karaoke in a bar—which, when you think about it, is really stupid.And I really don't like talking on the phone. If I'm dialing someone, I feel like I'm bothering them, and it puts me off from doing it. Social anxiety is the most common phobia, because there are so many ways it can manifest. It doesn't seem like an evolved mechanism, but it is. Humans are very social, tribal creatures. We evolved in tight-knit communities, which is our evolutionary strength. When we're all working together, we can compete with any other animal. We can live together in massive cities with multiple millions of people living on top of one another, like in Cairo or Delhi. Even insects can't rival that level of population density without killing each other.

In the wild, if you're rejected, you're going to die pretty quickly. So we are very wary of others peoples judgement of us. The idea of being embarrassed or rejected—even if it's just singing karaoke—the brain does not like that idea. If you think of Hells Angels, they've rejected the rules of society, but they all dress exactly the same. So they still clearly have this strong compulsion to be part of a group, because the appraise of your peers is something the brain really wants. Anything that jeopardizes that is very unpleasant for the brain.

How does the brain reconcile something that we consciously know we shouldn't be afraid of but we're afraid of anyway?Well, when it comes to actual phobias, it's by definition an irrational fear. You can be afraid of clowns and also know a clown isn't going to sneak up and murder you in the street. That's not something clowns usually do, outside of Stephen King books. So if you encounter a clown and nothing bad happens, the brain should learn, "I saw a clown, nothing bad happened, clowns are not scary." But because it has the existing connection to fear, you get the fight-or-flight response. The brain floods you with adrenaline; you're trembling and tense, and your heart rate goes up. There's a strong physical response when you're afraid, and it's not pleasant. So the brain associates encountering the thing you're afraid of with the fear response, which makes your brain think the fear is justified. It's a feedback loop that only intensifies the fear.

Yikes. How do you overcome that?Systematic desensitization is one way. It gradually introduces you to the thing you're afraid of on a very slow basis, so you don't trigger the fear response. If you're afraid of spiders, [therapists] might show you a small picture of a spider. Then a plastic spider. Then a video of a live spider, then a small spider in a box, then a tarantula in a box, until you end up holding the spider. You get to the point where you're at your max level and tip it slightly further each time without triggering the fight-or-flight response.

This all makes sense for a primitive, threatening environment. But how does this inclination toward fear fit into our modern world?Well, it's a problem in our current environment. We're capable of a lot more abstract thoughts like planning, imagination, rationalization, predictions—all things that can trigger the fear response. For example, a lot of people are afraid of losing their job, especially if they hear about a downturned economy. That's not a thing that physically threatens you—there's no threat of death or injury, and there's no guarantee it'll even happen—but people are still very afraid. We can extrapolate to the extent that these wild predictions can trigger the same fear response as an actual physical threat would.

Things today are so complex that it's not just about surviving or finding enough food but about progressing your career or being liked by your friends or even having enough Twitter followers—all things that people now care about and can be fearful of. There are so many things to worry about that we're constantly worried.

So information overload has turned into anxiety overload?Exactly. The modern world provides so much information now. Especially with the internet, it seems like the world is getting a lot worse, but statistically it's improving. Now that we have a lot more exposure to other people and other things happening in the world, we have a lot more awareness of things going badly.

In the book, you write about panic attacks, which you describe as "the brain cutting out the middle man and inducing fear reactions in the absence of any feasible cause." Is there an evolutionary reason for that?The brain hasn't evolved to do all the things it does for a specific purpose. It's more like a consequence of the way it's arranged itself. So, people ask, "Why has the brain got two hemispheres?" and there's no real purpose; it just happened by chance. Evolution isn't about what's the best option; it's just about what does the job well enough.

With panic attacks, there are many theories: You might start off with a strong tendency toward phobias. You could have an overdeveloped fear response system, or rather an overdeveloped part of the brain, like the prefrontal cortex, which would override the more basic responses and would suppress a fear response. It could be a traumatic experience that gives you a strong, fearful memory [that induces a panic attack]. Or it could be a glitch in one area of the brain where, if you're already prone to fearful responses, you don't even need anything specific to trigger them just due to a quirk of brain chemistry. It sounds like I'm describing the brain backfiring, and it's obviously more complex than that. But basically, there's no real reason for panic attacks. They don't serve a purpose. They happen when the fear system becomes unpredictable and isn't associated with an actual fear trigger and response.

It seems like a lot more people suffer from anxiety disorders and panic attacks now than, say, 50 years ago. Is anxiety socially contagious?There's definitely potential for that. We take so many cues from other people. That's why you get things like mob mentality. A few years ago, there was a riot in London when a a kid threw a fire extinguisher off the roof. Could've killed someone. He wouldn't have done that otherwise, but in part of a highly aroused group, you become part of that. So if you are constantly experiencing other people expressing anxiety, whether you logically agree with it or not, your brain subconsciously logs it. This is especially true with the internet, where you can constantly see peoples' neuroses laid bare. If someone else has arrived at these conclusions and your brain takes them in to a certain extent, over time it could create a low-level anxiety.

If our brains evolved to be super fearful, do you think it's possible for our brains to evolve toward chilling out?To say we'll evolve out of it is a hard one. Evolution takes so long, especially with something that doesn't kill you, and anxiety is not necessarily something that does that. But the brain is very good at getting used to things. It's called habituation. Anything that's constant or reliable, the brain stops paying attention to it or giving it weight. For example, soldiers can fall asleep in war zones whereas if you and I were to drop into a war zone, we'd be constantly panicked. So if we get to a point where technology or the pace becomes more consistent, I can see a world where we become more used to things and the things that make us so anxious right now are not a problem anymore.

In the meantime, what are some things people can do to make their brains less anxious?Each individual brain is so different than anyone else's that providing a blanket solution is actually not very helpful. But the obvious answer is: If something's upsetting or scaring you, then dissociate yourself from it for a while. Some people say reading their Twitter or Facebook feeds make them depressed; well, if that's the case, detach for a while. The brain also gets stressed by loss of control—perceived or real. That's where superstition comes from. It gives you the illusion of being in charge of your world. So do something to give yourself a sense of control again.